1. Field of the Invention The present invention relates to providing a robust error recovery due to data losses incurred during transmission of signals. More particularly, the present invention relates to a method of time-varying randomization of data used in facilitating a robust error recovery.
2. Art Background
A number of techniques exist for reconstructing lost data due to random errors that occur during signal transmission or storage. However, these techniques cannot handle the loss of consecutive packets of data. Consecutive loss of packets of data is described in the art as burst error. Burst errors result in a reconstructed signal with such a degraded quality that it is easily apparent to the end user. Additionally, compression methodologies used to facilitate high speed communications compound the signal degradation caused by burst errors, thus adding to the degradation of the reconstructed signal. Examples of burst error loss affecting transmitted and/or stored signals may be seen in high definition television (xe2x80x9cHDTVxe2x80x9d) signals, mobile telecommunication applications, as well as video storage technologies including video disk and VCRs.
For example, the advent of HDTV has led to television systems with a much higher resolution than the current standards proposed by the National Television Systems Committee (xe2x80x9cNTSCxe2x80x9d). Proposed HDTV signals are predominantly digital. Accordingly, when a color television signal is converted for digital use it is common that the luminance and chrominance signals may be digitized using eight bits. Digital transmission of NTSC color television signals may require a nominal bit rate of about two-hundred and sixteen megabits per second. The transmission rate is greater for HDTV, which may nominally require about 1200 megabits per second. Such high transmission rates may be well beyond the bandwidths supported by current wireless standards. Accordingly, an efficient compression methodology is required.
Compression methodologies also play an important role in mobile telecommunication applications. Typically, packets of data are communicated between remote terminals in mobile telecommunication applications. The limited number of transmission channels in mobile communications requires an effective compression methodology prior to the transmission of packets. A number of compression techniques are available to facilitate high transmission rates.
Adaptive Dynamic Range Coding (xe2x80x9cADRCxe2x80x9d) and Discrete Cosine Transform (xe2x80x9cDCTxe2x80x9d) coding provide image compression techniques known in the art. Both techniques take advantage of the local correlation within an image to achieve a high compression ratio. However, an efficient compression algorithm may result in compounded error propagation because errors in an encoded signal are more prominent when subsequently decoded. This error multiplication may result in a degraded video image that is readily apparent to the user.
The present invention includes a system and method to encode data to maximize subsequent recovery of lost or damaged encoded data. In one embodiment, a current block of data is randomized in accordance with data from the current block and data from at least one temporally adjacent block of data. In one embodiment, randomized data is derandomized using the current block of data and data from at least one temporally adjacent block. In addition, in one embodiment, decoding of the current block and the adjacent block is delayed in order to facilitate recovery of lost or damaged compression parameters of encoded data.